Plastic film zipper bag having straightened heat seals
AssigneeMobil Oil Corporation
InventorF. John Herrington, Jr.
Life of this patent
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Abstract
In the manufacture of thermoplastic film zipper bags and the like heat sealing the film to the zipper produces a seal line that shrinks, resulting in unsightly apearance. A system and method are disclosed for restoring the shrunk seal line to its orginal length by corrugating and stretching it between mating teeth. A method is also disclosed for restretching the seal without corrugation.
Claims1
A plastic film zipper bag wherein the zipper comprises a pair of extruded flexible plastic strips having reclosable interlocking profile elements in the form of rib and groove elements on the respective strips, each of the extruded strips including a thin fin section depending therefrom and heat sealed to the plastic film thereby causing the film to shrink along the line of the seal, the shrunk seal being selectively stretched back to the original length by pressing the seal between corrugating teeth thereby elongating the shrunk seal to the original length resulting in a straight seal with an embossed appearance of zipper teeth.
Dependencies are inferred from the claim text.